The invention relates to a device for the selection and detection of at least two spectral regions in a beam of light, having a selection device and a detection device. In particular, the present invention relates to a device of the type under discussion which is suitable for use in confocal fluorescence microscopy.
"Proceedings of Scanning, Vol. 13, Supplement I, 1991, pages I-76 and I-77" to be found in the literature disclosed a confocal fluorescence microscope which can be used to detect the spectral region of a dye. A beam of light generated by a laser is guided with the aid of optical units to an object to be microscoped and reflected from the latter, or excites fluorescent materials there. The reflected or fluorescent beam of light is coupled out by means of a beam splitter and fed to a detector via an optical filter. The filter fulfills the task of cutting out the spectral region of the dye. If the relevant dye is contained in the object to be microscoped, it is detected by the detector due to the high intensity. Consequently, it is possible in this way in the case of a biomedical application, for example, to detect dyed cells or cell structures in an object.
It is also already known to use the previously described microscoping technique over a wider scope. Thus, for example, different cell constituents are dyed simultaneously with two or more dyes, in order to be able to determine or investigate the spatial correlation of the cell constituents. However, it is necessary in the framework of this application to cut out, or select the different spectral regions of the respective dyes from the total reflected beam of light. For this purpose, use has been made to date of beam splitters and optical filters which are exactly tuned to the respective spectral region. Each cut-out beam of light is then fed in a way known per se to a detector provided specially for the purpose.
The previously dressed device, from which the invention present here proceeds, which serves to select and detect at least two spectral regions in a beam of light has the very substantial disadvantage that a separate filter is required for each dye. With regard, in particular, to the possibility of detecting different dyes or dye combinations, the consequence of this is that a multiplicity of filters must be provided as dictated by the system. A further disadvantage of the known device is to be seen in that the intensity of the beam of light reflected from the object is reduced by the filters. The consequence of this, in turn, is that increased optical and, if appropriate, electronic demands have to be placed on the detectors for reliable selection and detection of spectral regions.